The objective of this research is the investigation of the role of DNA repair in radiation-induced mutagenesis and transformation in a mammalian cell line. The effects of stationary holding recovery on the frequencies of these processes is currently under investigation. The characteristics of DNA repair in the cells will be studied by measuring error-free and error prone reactivation of irradiated virus by the host cells under various conditions. We also hope to isolate repair-defective strains following mutagenesis of the cells with ethylmethane sulfonate (EMS) and enrichment using a host-cell viral reactivation suicide technique. Changes in the frequencies of carcinogenesis and mutagenesis in the wild-type cells are compared to the repair-deficient strains will then be correlated to deficiencies in specific repair processes.